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Problem Solving/SQL

[ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค] MYSQL - JOIN

by DevIseo 2022. 7. 23.

[ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค] MYSQL - JOIN

1. ์—†์–ด์ง„ ๊ธฐ๋ก ์ฐพ๊ธฐ

https://school.programmers.co.kr/learn/courses/30/lessons/59042

 

ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค

์ฝ”๋“œ ์ค‘์‹ฌ์˜ ๊ฐœ๋ฐœ์ž ์ฑ„์šฉ. ์Šคํƒ ๊ธฐ๋ฐ˜์˜ ํฌ์ง€์…˜ ๋งค์นญ. ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค์˜ ๊ฐœ๋ฐœ์ž ๋งž์ถคํ˜• ํ”„๋กœํ•„์„ ๋“ฑ๋กํ•˜๊ณ , ๋‚˜์™€ ๊ธฐ์ˆ  ๊ถํ•ฉ์ด ์ž˜ ๋งž๋Š” ๊ธฐ์—…๋“ค์„ ๋งค์นญ ๋ฐ›์œผ์„ธ์š”.

programmers.co.kr

SELECT A.ANIMAL_ID,A.NAME
FROM ANIMAL_OUTS A 
LEFT JOIN ANIMAL_INS B
ON A.ANIMAL_ID = B.ANIMAL_ID
WHERE B.ANIMAL_ID IS NULL
ORDER BY ANIMAL_ID

 

2. ์žˆ์—ˆ๋Š”๋ฐ์š” ์—†์—ˆ์Šต๋‹ˆ๋‹ค

https://school.programmers.co.kr/learn/courses/30/lessons/59043

 

ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค

์ฝ”๋“œ ์ค‘์‹ฌ์˜ ๊ฐœ๋ฐœ์ž ์ฑ„์šฉ. ์Šคํƒ ๊ธฐ๋ฐ˜์˜ ํฌ์ง€์…˜ ๋งค์นญ. ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค์˜ ๊ฐœ๋ฐœ์ž ๋งž์ถคํ˜• ํ”„๋กœํ•„์„ ๋“ฑ๋กํ•˜๊ณ , ๋‚˜์™€ ๊ธฐ์ˆ  ๊ถํ•ฉ์ด ์ž˜ ๋งž๋Š” ๊ธฐ์—…๋“ค์„ ๋งค์นญ ๋ฐ›์œผ์„ธ์š”.

programmers.co.kr

SELECT A.ANIMAL_ID,A.NAME
FROM ANIMAL_INS AS A
JOIN ANIMAL_OUTS AS B
WHERE A.ANIMAL_ID=B.ANIMAL_ID AND A.DATETIME >= B.DATETIME
ORDER BY A.DATETIME

 

3. ์˜ค๋žœ ๊ธฐ๊ฐ„ ๋ณดํ˜ธํ•œ ๋™๋ฌผ(1)

https://school.programmers.co.kr/learn/courses/30/lessons/59044

 

ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค

์ฝ”๋“œ ์ค‘์‹ฌ์˜ ๊ฐœ๋ฐœ์ž ์ฑ„์šฉ. ์Šคํƒ ๊ธฐ๋ฐ˜์˜ ํฌ์ง€์…˜ ๋งค์นญ. ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค์˜ ๊ฐœ๋ฐœ์ž ๋งž์ถคํ˜• ํ”„๋กœํ•„์„ ๋“ฑ๋กํ•˜๊ณ , ๋‚˜์™€ ๊ธฐ์ˆ  ๊ถํ•ฉ์ด ์ž˜ ๋งž๋Š” ๊ธฐ์—…๋“ค์„ ๋งค์นญ ๋ฐ›์œผ์„ธ์š”.

programmers.co.kr

SELECT NAME, DATETIME
FROM ANIMAL_INS
WHERE ANIMAL_ID NOT IN (
    SELECT ANIMAL_ID
    FROM ANIMAL_OUTS
)
ORDER BY DATETIME
LIMIT 3

 

4. ๋ณดํ˜ธ์†Œ์—์„œ ์ค‘์„ฑํ™”ํ•œ ๋™๋ฌผ

 

https://school.programmers.co.kr/learn/courses/30/lessons/59045

 

ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค

์ฝ”๋“œ ์ค‘์‹ฌ์˜ ๊ฐœ๋ฐœ์ž ์ฑ„์šฉ. ์Šคํƒ ๊ธฐ๋ฐ˜์˜ ํฌ์ง€์…˜ ๋งค์นญ. ํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค์˜ ๊ฐœ๋ฐœ์ž ๋งž์ถคํ˜• ํ”„๋กœํ•„์„ ๋“ฑ๋กํ•˜๊ณ , ๋‚˜์™€ ๊ธฐ์ˆ  ๊ถํ•ฉ์ด ์ž˜ ๋งž๋Š” ๊ธฐ์—…๋“ค์„ ๋งค์นญ ๋ฐ›์œผ์„ธ์š”.

programmers.co.kr

SELECT A.ANIMAL_ID, A.ANIMAL_TYPE, A.NAME
FROM ANIMAL_INS as A JOIN ANIMAL_OUTS as B
WHERE A.ANIMAL_ID = B.ANIMAL_ID AND A.SEX_UPON_INTAKE !=B.SEX_UPON_OUTCOME
ORDER BY A.ANIMAL_ID

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